Atmospheric controlled container

ABSTRACT

A container for carrying atmospherically sensitive items or perishables is provided that keeps the damage to the items at a minimum and also allows for extended duration containment of the items while minimizing quality degradation thereof, such as for shipping, display and/or storage. The container has a strong, robust container body such as formed of rigid walls that cooperate to form an internal space in which the items are received in a protected manner. To allow for a controlled exchange of gasses between the container interior space and the ambient exterior environment in accordance with the needs of the atmospherically sensitive items contained in the container for maintaining the product quality for long duration containment thereof, at least one of the container walls includes a window or port opening at which a semi-permeable membrane is mounted.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a utility patent based on U.S. provisional application Serial No. 60/389,372, filed Jun. 17, 2002, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

[0002] The invention relates to containers and, more particularly, to containers for atmospherically sensitive items.

BACKGROUND OF THE INVENTION

[0003] Fresh produce is commonly packaged in bags made of flexible film material for retail sale. As the sealed produce in the bag is generally highly perishable largely due to the respiration process, these bags have been formed with films that are semi-permeable to gas transmission for gas exchange with the external ambient environment to maximize the shelf-life of the produce. Patches of the semi-permeable film or membrane can also be applied to packages over small holes formed in the package film to permit gas exchange therethrough.

[0004] The permeability of these membranes can be specifically designed to keep the atmosphere in the package at conditions that maintain long term freshness of the produce. The gas transmission properties of the membranes can be matched to the particular type of produce so that the respiration characteristics thereof do not generate atmospheric conditions in the package that cause accelerated deterioration of the produce. Different fruits and vegetables, and even different varieties of a given fruit or vegetable, vary in their respiration rates. For example, asparagus, mushrooms and broccoli have higher respiration rates and thus tend to be more perishable than nuts, onions and potatoes which have lower respiration rates.

[0005] Respiration involves the consumption, using atmospheric oxygen (O₂), of carbohydrates and organic acids and the consequent production of metabolic energy, heat, carbon-dioxide (CO₂) and moisture vapor. The semi-permeable membranes are configured to primarily manipulate the amount of O₂ and CO₂ within the packaging based on the respiration rates of the produce and the ideal atmosphere for maintaining their freshness. Other perishable packaged food include such things as fish, beef and poultry that do not respire. The membranes that are ideal for use with these perishable food products will be different as the optimum gas concentration for keeping these packaged items best preserved will vary from each other, as well as from that required with respect to fruits and vegetables which respire.

[0006] One significant problem with current modified atmosphere packaging, whether the permeable film be used to form the package or only a patch thereon, is the risk of punctures which would destroy the controlled atmosphere inside the package. In a like manner, long-haul transport of the produce would not be feasible simply using the flexible film packages without also encasing them in some sort of more rigid container. Currently, plastic-lined cardboard boxes are commonly employed for shipping produce, although atmospheric-controlled shipping containers are also known, such as disclosed in U.S. Pat. No. 5,960,708 to the present applicants, which is incorporated by reference as if reproduced in its entirety herein. However, shipping containers such as in the '708 patent do not contemplate continuous gas exchange with the ambient atmosphere, and otherwise are not particularly well-suited to reuse with various types of perishables with different atmospheric requirements for the long duration preservation thereof.

[0007] Accordingly, there is a need for a strong container that can carry atmospherically sensitive items or perishables therein with a minimum of physical damage thereto while maintaining atmospheric conditions in the container conducive to long-term containment of the perishables in a high quality manner. Further, a need exists for a modified atmosphere container that can be readily adapted for containing different types of perishable items therein while maintaining the atmosphere in the container optimal for the long duration containment thereof.

SUMMARY OF THE INVENTION

[0008] In accordance with the present invention, a container for carrying atmospherically sensitive items or perishables is provided that keeps the damage to the items at a minimum and also allows for extended duration containment of the items while minimizing quality degradation thereof, such as for shipping, display and/or storage. The container has a strong, robust container body such as formed of rigid walls that cooperate to form an internal space in which the items are received in a protected manner. The walls of the container body are sufficiently rigid to protect the items against impacts with the container such as can occur during handling and shipping thereof. To allow for a controlled exchange of gasses between the container interior space in which the atmospherically sensitive items are carried and the ambient exterior environment, at least one of the walls includes a window or port opening at which a semi-permeable membrane is mounted.

[0009] The membrane maintains the atmospheric conditions in the internal space at an optimized state for allowing the atmospherically sensitive items to be contained therein for extended periods of time without the typical degradation that would otherwise be seen over this same time period. The membrane allows gasses from the external atmosphere and those from the internal container space to be exchanged such that the atmospheric conditions that would be present in the container space are varied in accordance with the needs of the items contained therein for maintaining the product quality for long duration containment thereof. Accordingly, the present container provides both physical protection to the contained items such as due to impacts with the container and extends the shelf-life of the products carried in the container, such as by reducing the spoilage rate of perishable items that may be contained therein.

[0010] The semi-permeable membrane is preferably mounted to the container wall so that damage to the membrane itself is minimized. In particular, since the membrane is generally a more flexible thin film member in comparison to the stronger, thicker, more rigid walls of the container, there is a risk of the membrane being punctured by engagement with surrounding objects, particularly those with sharp edges and the like.

[0011] In one form of the present invention, a grate assembly is provided to protect the underlying membrane against damage when secured to the container wall about the port opening thereof. In another form, a modular unit carries the membrane therein with the modular unit and wall having a releasable or detachable connection formed therebetween for removal and replacement of the unit onto the container. In both the grate assembly and the modular unit, small openings or narrow slots are formed in an outer, substantially rigid protective member thereof so that airflow can access the underlying membrane for gas exchange between the container interior space and ambient atmosphere. Thus, only relatively small objects that can fit though these openings or slots will have access to the membrane. In this manner, in either the grate assembly or modular unit, the membrane is protected from large bore, mechanical punctures that would destroy the controlled atmosphere inside the container.

[0012] In another form of the invention, the container includes a plurality of membranes that are each coded according to the manner in which they regulate gas exchange to allow ease of use in providing optimized atmospheric conditions in the container interior for specific types of perishable items. A removable mount such as the previously-described grate assembly or modular unit is provided for releasable attaching a selected one of the membranes to the container body at the port opening. In this manner, atmospheric conditions in the container space can be readily tailored to the perishable item that is to be carried thereby.

[0013] More specifically, if the items are fresh-cut produce, then the respiration characteristics will govern the membrane that is to be selected for proper manipulation of the levels of oxygen and carbon dioxide within the container. In this regard, the membrane is configured to handle the otherwise changing atmospheric conditions in the container space over time due to produce respiration by creating an equilibrium atmosphere in the container space with oxygen levels low enough and carbon dioxide levels high enough to be beneficial to the produce and not injurious. For instance, if the item is broccoli which has a high respiration rate, then a membrane is selected that maintains atmospheric conditions in the container space such that oxygen levels are preferably between approximately two and five percent and the carbon dioxide levels are between approximately fifteen and twenty percent. If the vegetables or fruits to be carried in the container have a medium or low respiration rate, then a different membrane is selected accordingly.

[0014] On the other hand, if the container is carrying food that does not respire, then a different membrane may be in order. For example, a membrane that maintains oxygen levels at approximately eighty percent and carbon dioxide levels at approximately twenty percent would be preferable if beef is carried in the container. If it is poultry that is carried in the container space, then a membrane should be selected to provide concentrations of carbon dioxide at about twenty-five percent and nitrogen at about seventy-five in the container space. Since the oxygen level normally present in the atmosphere is approximately twenty-one percent, the membranes for both beef and poultry will preferentially allow passage of oxygen into the container with the membrane for beef allowing a much greater exchange of oxygen to reach the desired level in the container space. Similarly, to obtain the desired elevated carbon-dioxide levels in the container space over the less than one percent level present normally in the atmosphere, the membrane for beef preferentially allows passage of large amounts of carbon dioxide from the external atmosphere into the container space until the desired equilibrium level thereof is reached. As is apparent, the membrane can be selected based on other perishable items such as flowers and atmospherically sensitive electronic equipment.

[0015] The codes or indicia of the membranes for the different atmospherically sensitive items can be colors that are each associated with different products that may be carried in the container. For example, a red membrane can be for strawberries, a green membrane for broccoli, and a brown membrane for beef. In this manner, a user can readily pick out the appropriate color membrane for use with the container based on the product to be carried therein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a perspective view of containers in accordance with the present invention stacked on a pallet for shipping;

[0017]FIG. 2 is an enlarged perspective view of one of the containers of FIG. 1 showing a pair of grate assemblies for semi-permeable gas membranes secured to a wall of the container;

[0018]FIG. 3 is an enlarged, exploded, rear perspective view of the grate assembly of FIG. 2 showing the membrane to be sandwiched between a pair of grate members and a port opening in the container wall to which the grate assembly is releasably secured;

[0019]FIG. 4 is a front elevational view of the grate assembly secured to the container wall;

[0020]FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 4 showing the permeable membrane clamped between the grate members via removable fasteners;

[0021]FIG. 6 is a cross-sectional view taken along line 6-6 of FIG. 4 showing gas exchange between the container internal space and external ambient environment through the semi-permeable membrane;

[0022]FIG. 7 is a fragmentary cross-sectional view taken along line 7-7 of FIG. 4 showing one of the removable fasteners;

[0023]FIG. 8 is a perspective view of an alternative container in accordance with the present invention configured to be used as a crisper bin with a pair of crisper bin containers shown in compartments of a refrigerator;

[0024]FIG. 9 is a view similar to FIG. 8 showing one of the crisper bin containers pulled out from the refrigerator compartment with the lid of the container pivoted open;

[0025]FIG. 10 is a perspective view of the crisper bin container of FIGS. 8 and 9 showing a modular unit carrying one of the semi-permeable membranes therein secured to a front wall of the container;

[0026]FIG. 11 is an enlarged elevational view of the modular unit showing a front grate surface thereof;

[0027]FIG. 12 is a cross-sectional view taken along line 12-12 of the modular unit showing the membrane with gas exchange occurring between the container interior space through the membrane and the grate surface of the unit;

[0028]FIG. 13 is a cross-sectional view taken along line 13-13 of FIG. 12 showing a shank of the modular unit fit in the port opening and a bayonet connection formed between the shank and container wall about the opening;

[0029]FIG. 14 is a rear elevational view taken along line 14-14 of FIG. 12 showing the unit releasably secured to the wall about the opening thereof;

[0030]FIG. 15 is a plan view of the container body showing the configuration of the bottom wall of the container for stacking purposes;

[0031]FIG. 16 is a cross-sectional view taken along line 16-16 of FIG. 15 showing a laterally extending lip flange having an upwardly extending rib projection;

[0032]FIG. 17 is a cross-sectional view of a generally U-shaped seal attached at the outer perimeter of a lid for the container body;

[0033]FIG. 18 shows the lid seated onto the container body with the rib projection tightly engaged with the seal member for sealing of the container interior space from the external ambient environment; and

[0034]FIG. 19 is a cross-sectional view similar to FIG. 18 except showing the configuration seal arrangement at a corner of the container.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035]FIGS. 1 and 2, a container 10 having a semi-permeable membrane 12 mounted thereto in accordance with the present invention is illustrated. The preferred and illustrated container 10 has a robust construction including a housing member or body 14 for forming an internal space 16. The container 10 can be closed off by an upper housing member or lid 18. As shown, the container body 14 has a box shape including a bottom wall 20 with walls generally designated 22 upstanding from the periphery thereof, such as at a slight outward taper for stacking purposes as for nesting of several of the bodies or base member 14 together. The upstanding walls 22 form a large access opening 24 at upper ends 26 thereof that leads to the interior container space 16. The lid 18 is sized to seat on the upper ends 26 of the walls 22 for closing the opening 24 and sealing the container space 16 via seal arrangement 28, as best seen in FIGS. 17-19 and as will be described more fully hereinafter. Accordingly, in the preferred form, the lid 18 forms the container upper wall which closes off the box container 10 with the walls 18-22 bounding the container space 16 therein.

[0036] The container walls of the body 14 and lid 18 are preferably of a strong, rigid construction so that they are self-supporting and resist deformation when impacted or otherwise loaded. The container members 14 and 18 can be molded from a high strength composite plastic material such as KEVLAR® to withstand extremes in pressures and temperatures, for example, such as those found in airborne transport. The high strength container 10 also provides for continuous, controlled gas exchange with the external ambient environment via the membrane 12 mounted to a port opening 30 in one of the walls, and preferably one of the upstanding wall 22 thereof, as can be seen best in FIGS. 2 and 3. The membranes 12 are commercially available from many suppliers, with applicants assignee's supplier being Chantler Packaging out of Mississauga, Ontario in Canada, who manufactures a PEAKFresh™ product line of semi-permeable membranes 12. With the lid 18 seated on the container body 14 to substantially seal the container interior space 16 from the ambient environment, all gas exchange will occur through the membrane 12 at the port opening 30. Thus, the present container 10 provides product protection due to the high strength construction of the body 14 and lid 18 while at the same time extending product shelf-life thereof by the controlled gas exchange between the external environment and the container internal space 16 provided by the membrane 12.

[0037] The membrane 12 is preferably mounted to the container wall 22 by a removable mount, generally designated 31, that provides the membrane 12 with a releasable connection to the container 10 so that the membrane 12 can be changed out with another like membrane or a different membrane such as when the container 10 is to carry different products therein. In this way, the container 10 is more universally usable with different products, be they produce or other atmospherically sensitive items.

[0038] The membranes 12 can be provided in a set with the membranes 12 coded based on the product with which they are to be used. One or several membranes 12 of a particular construction or configuration each coded identically to indicate the product type for which their use is optimal can be provided in a kit. For example, each membrane kit can come with two or more identical membranes 12 of each type in case one membrane 12 is damaged in use, and there can be several different types for the different products that may be packaged in the container 10. To this end, body 12 a of the membrane 12 can be formed of different color semi-permeable films with each color corresponding to a particular product to be carried. Thus, a set of membranes 12 can include, for example, red membranes 12 for a red fruit or vegetable such as red strawberries or red peppers, green membranes 12 for green apples or green cucumbers, and brown membranes 12 for pears or onions. As is apparent, the color coding scheme adopted can be intuitive as by general matching of the membrane color to that of the product for which its use is optimal for use. Other coding can be used, such as simple indicia that includes printing text or graphics representative of the product on the film, although coloring the film body 12 a is preferred.

[0039] As shown in FIG. 3, in one form the mount 31 includes a grate assembly 32 that can readily be detached from the wall 22 as by use of a driver to remove fasteners 34 that secure the grate assembly 32 thereto so as to form the releasable connection of the membrane 12 to the wall 22. In addition, the grate assembly 32 also protects the thin film membrane 12 from damage that otherwise could occur due to its exposed position on an outer container wall 22.

[0040] More particularly and referring to FIGS. 3 and 4, the grate assembly 32 has an outer rigid protective member in the form of grate portion or member 36 which substantially covers the membrane 12 when the grate assembly 32 is fastened to the wall 22. The grate member 36 has small openings or slots 38 formed therein to expose the underlying membrane 12 to the ambient atmosphere external of the container space 16. Accordingly, only those items that are small enough to fit through the relatively narrow slot openings 38 can physically access to the membrane 12 significantly reducing the potential for damage thereto.

[0041] The grate assembly 32 preferably clamps the membrane 12 between the two rigid grate members including the outer grate member 36, and an inner rigid grate member 40 so as to firmly hold and sandwich the membrane 12 therebetween, as shown in FIGS. 5 and 6. The grate members 36 and 40 can have bodies 36 a and 40 a having a flat, plate-like construction and formed of a metallic or hard plastic material. Referring again to FIG. 3, it can be seen that the inner grate member 40 is provided with small openings in the form of slots 42 similar to those of the outer grate member 36. As shown, the slot openings 38 and 42 formed in the respective outer and inner grate member bodies 36 a and 40 a extend transversely thereacross with their peripheries arranged in a circular pattern substantially matching the outer shape of the membrane 12. The slots 38 and 42 are separated on either half of the circular pattern thereof by respective central, vertical bar portions 44 and 46 of the grate member bodies 36 a and 40 a. In this way, when the grate members 36 and 40 are fastened together with the membrane 12 clamped therebetween, the aligned slots 38 and 42 and bar portions 44 and 46 allow for air flow through the grate members 36 and 40 that is unimpeded except for the membrane 12 through which gases are selectively passed, as best seen in FIGS. 5 and 6.

[0042] To keep air from leaking from the container 10 through the port opening 30 without passing through the membrane 12, the grate assembly 32 preferably incorporates a resilient seal member 48 between rigid inner grate member body 40 a and the outer surface 22 of the container wall 22 in which the port opening 40 is formed. Referring to FIG. 3, the seal member 48 is provided with a central opening 50 having a diameter slightly greater than that of the inner grate member 40, with the diameter of the generally circular grate member 40 approximately the same as that of the membrane 12 and the circular peripheral pattern of the slots 38 formed in the outer grate member 36. The diameter of the grate members 36 and 40 and the membrane 12 are approximately the same as that of the generally circular port opening 30. Accordingly, air flow that would otherwise may occur about the grate member 40, membrane 12 and grate member 36 via the port opening 30 is substantially blocked by the provision of the seal member 48 to minimize leakage between the container space 16 and the external environment through the port opening 30.

[0043] The seal member 48 has a generally flat body 48 a that can be of an elastomeric or rubber material for being clamped and compressed tightly against the container wall surface 22 a about the port opening 30 when the grate assembly 32 is releasably secured thereto via the fasteners 34. The fasteners 34 can be screws having threaded shanks 52 that are received in internally threaded nuts 54. The illustrated nuts 54 are provided with an outer knurled surface 54 a for being press-fit in apertures 56 of the outer grate member 36, as shown in FIG. 7. Alternatively, the apertures 56 themselves could be provided with threads, or cap members 58 such as shown in FIGS. 4-6 could be provided with internal threads for receiving the shanks threaded therein. The illustrated cap members 58 are preferably integrally formed with the grate member 36 aligned with the apertures 56 and projecting outwardly therefrom. In this way, the cap members 58 form pocket apertures 56 in which the nuts 54 are fit for covering the nuts 54 and shank ends received therein.

[0044] In the preferred and illustrated form, the general configuration of the seal member body 48 a is substantially the same as that of the outer grate member 36 but for the large central opening 50 formed in the seal body 48 instead of the plurality of slots 38 formed at the corresponding central position in the grate body 36 a. To this end, the grate member body 36 a includes enlarged corner portions 60 in which the apertures 56 are formed, and the seal member body 48 a includes corresponding enlarged corner portions 62 through which apertures 64 are formed. Instead of the enlarged corner portions 60 and 62, the more circular shaped body 40 a of the inner grate member 40 is provided with a pair of diametrically opposed, small tab portions 66 in which small apertures 68 are formed. The outer grate member 36 includes small mounting bosses 70 sized and positioned about the circular periphery of the slot openings 38 to fit into the apertures 68 for proper positioning of the inner grate member 40 with respect to the outer grate member 36 so that the slot openings 38 and 42 are aligned when the grate assembly 32 is secured to the container wall 22.

[0045] Accordingly, to secure the grate assembly 32 on the container wall 22 about the port opening 30 formed therein, the membrane 12 is sandwiched between the grate members 36 and 40 by positioning it on the outer grate member 36 so that its circular periphery is substantially aligned with the circular periphery of the slots 38. The inner grate member 40 is then positioned on the membrane 12 and in proper alignment with the grate member 36 by fitting the bosses 70 into the apertures 68 in the grate member tabs 66.

[0046] Next, the shanks 52 of the screw fasteners 34 are advanced from the interior container space 16 into through apertures 72 formed in the container wall 22 about the port opening 30 in a pattern substantially matching that of the apertures 56 and 64 formed in the grate and seal members 36 and 48. With the shanks 52 projecting beyond the outer surface 22 a of the container wall 22, the seal member 48 is then placed over the projecting shank portions 52 a by inserting them through the apertures 64 thereof. Thereafter, the assembled grate members 36 and 40 and membrane 12 sandwiched therebetween are positioned on the end portions 52 a of the shanks 52 projecting beyond the seal member 48 via the nuts 54 in the grate member pocket apertures 56. While holding the grate assembly 32 such as by cap portions 58 thereof to keep the grate assembly 32 from turning, the screws fasteners 34 are tightened until the enlarged heads 74 are seated tightly against inner surface 22 b of the container wall 22. Tightening of the screws 34 draws the grate assembly 32 including the rigid grate members 36 and 40 tightly against the more flexible resilient seal member 48 to compress it between the grate members and the outer surface 22 a of the container wall 22 so that any gas leakage about the grate assembly 32 is minimized, as previously discussed.

[0047] To change membranes 12, the screw fasteners 34 are loosened to allow the grate members 36 and 40 along with the sandwiched membrane 12 to be pulled off the screw shanks 52. The membrane 12 is accessible by separating the grate members 36 and 40 to pull the bosses 70 of the outer grate member 36 out of the apertures 68 of the inner grate member 40. In this manner, the membrane 12 that is to be employed with the container 10 can be selected based on its gas exchange properties so that the environment in the container space 16 is optimized for the product to be carried therein. Alternatively, the grate members 36 and 40 can be more permanently attached as by snap-fitting or welding the two together with the membrane 12 therebetween to form a membrane unit or module. Several such modules can be available with different membranes 12 that are suited for use with a particular product, as previously has been described.

[0048] The container 10 can be adapted for use in a number of different applications including as a shipping or storage container as well as a smaller version for retail display and sale. Another adaptation is shown in FIGS. 8 and 9 with a container 76 provided in a form that enables its use as a crisper bin in a common household refrigerator 78. As shown, the refrigerator 78 includes lower crisper bin compartments 80 in which a pair of the crisper bin containers 76 can be slidingly fit in side-by-side relation. As best seen in FIG. 10, the crisper bin containers 76 have a generally rectangular box configuration similar to the previously described container 10 with a bottom wall 82 and upstanding generally vertical walls from the periphery thereof including parallel side walls 82 and 84 and parallel front and back walls 86 and 88 interconnecting the side walls 82 and 84 to form the container body or base, generally designated 90.

[0049] Whereas the lid 18 of the container 10 generally was separable from the body 14, the crisper bin container 76 preferably has corresponding lid member 92 pivotally connected to the body 90 as by hinge 94. In the illustrated form, the hinge 94 is located at the rear of the body 90 and lid member 92 adjacent the rear wall 88, although the lid 94 could be provided at positions intermediate along its length so that only a portion thereof can be pivoted open. The hinge 94 can include a pair of pivot pins 96 at either container side, one of which is shown in FIG. 10 that is substantially fixed to the container body 90 and also rotatively received in enlarged bearing portions 98 at the rear, opposite sides of the lid member allowing the lid 92 to be pivoted thereabout.

[0050] The lid 92 can include a raised handle 100 projecting up from its upper surface 92 a so as to leave a gap 102 therebetween. In this manner, a person wanting to pivot the lid 92 open can grasp the handle 100 with their fingers extending through the space 102. The lid 92 can also be provided with a forwardly projecting handle portion 104 that extends beyond the front wall 86 and in a general oblique downward direction so that a user can easily fit their fingers under the handle portion 104 for pulling the crisper bin container 76 out from its stowed position in the refrigerator compartment 80 therefor.

[0051] The container body walls 82-88 at their upper ends form an access opening 106 leading to the container interior space 108. The lid 18 has a rectangular size to fit on the upper ends of the walls 82-84 for closing off the rectangular access opening 106 formed thereby. Referring to FIGS. 15 and 16, the upper ends of the walls 82-84 can have a lip flange 110 formed thereat extending laterally outward and normal to the vertical walls 82-88 from the upper ends thereof. The lip flange 110 can include one-half of the seal arrangement 28 thereon, as shown best in FIGS. 16-19 and as will be described more fully hereinafter. The lip flanges 110 extending along the upper ends of the side walls 82 and 84 also allow the crisper bin container 76 to slide along rail structure provided in the refrigerator compartments 80 with the bottom side of the flanges 110 slidingly supported thereon.

[0052] The removable mount 31 for the membranes 12 for the crisper bin container 76 will next be described. The removable mount 31 is preferably in the form of a modular unit 112 having a releasable connection to the container body 90, and most preferably to the front wall 86 thereof. In this manner, the unit 112 is accessible for change-out without having to remove the crisper bin container 76 from the refrigerator 78. The releasable connection provided by the unit 112 is preferably a tooless connection so that a home user can replace the units 112 and thus membranes 12 carried thereby without the need for any specialized equipment or the like for such operation.

[0053] In the preferred and illustrated form, the modular unit 112 has a releasable connection between it and window opening 114 formed in the container front wall 86 in the form of a bayonet connection, as shown in FIGS. 12 and 13. Manifestly, other releasable connections such as a tooless threaded connection between the unit 112 and the wall opening 114 could also be provided. The unit 112 includes a generally cylindrical wall 116 having a rearwardly extending shank portion 118 and a forwardly extending head portion 120. At the forward end thereof, the unit head portion 120 includes a grated front surface 122 including slots 124 having their peripheries arranged in a circular pattern and separated by a bar portion 126 of the surface 122 intermediate their lengths, as best seen in FIG. 11. The membrane 12 is carried by the unit 112 residing against a radially inner annular wall 128 with the periphery of the membrane 12 sized to fit closely to the inside diameter of the unit cylindrical wall 116.

[0054] The rear shank portion 118 includes a small radial projection 130 extending therefrom and the wall 86 has a longitudinally extending slot 132 in which the projection 130 is received. At the inner end of the slot 132, a circumferentially extending slot 134 is provided. Accordingly, to releasably attach the unit 112 to the container wall 86, the projection 130 is lined up with the slot 132 to allow the unit 112, and more particularly the shank portion 118 thereof to be inserted into the opening 114 until the projection 130 bottoms out at the juncture 136 of the slots 132 and 134. The head portion 120 is provided with a radially enlarged flange 138 that is longitudinally positioned relative to the projection 130 so that it will abut against the wall 86 with the projection 130 aligned for being turned in the slot 134.

[0055] To secure the unit 112 to the wall 86, it is turned so that the projection 130 reaches the end of the circumferential slot 134 opposite the juncture 136 with the longitudinal slot 132, as shown in FIG. 13. For removing the unit 112 from the wall 86, the above-described steps are substantially reversed so that the unit 112 is first turned until the projection 130 is aligned with the longitudinal slot 132 and then pulled off from the wall 86 with the projection 130 traveling through the slot 132. Recesses 139 are formed around the periphery of the head portion 120 to allow a user to gain a good grip thereon for turning.

[0056] As previously mentioned, the seal arrangement 28 is provided between the lids and container bodies of both containers 10 and 76 so that air leakage from the container interior spaces 16 and 108, respectively, to the exterior ambient environment between the respective lids and container bodies is minimized. The seal arrangement 28 is provided at the upper ends of the containers upstanding walls. Accordingly, for crisper bin container 76 the container seal arrangement 28 includes a frustoconical base 140 on the lip flange 110. The base 140 has inclined sides 140 a and 140 b tapering upwardly and inwardly toward each other with a central nub projection 142 upstanding from the top surface 140 c of the base. The lid 92 has a downwardly opening pocket 144 formed about the perimeter thereof in which a generally U-shaped, resilient seal member 146 is secured. The pocket 144 is provided with lead-in inclined surfaces 144 a and 144 b having a taper corresponding to that of base sides 140 a and 140 b. Accordingly, when the lid 92 is seated on the upper ends of the walls 82-88, and particularly the lip flanges 110 thereof, the nub projection 142 will deform the central web 148 of the seal member 146 pushing it up into the pocket 144, as shown in FIGS. 18 and 19. In this manner, generally there is a double-layer of seal material between the closed lid 92 and the container body 90 to substantially provide a hermetic seal therebetween ensuring that substantially all air flow between the container space 108 and the ambient exterior environment is through the membrane 12 releasable attached at the container window opening 114 via modular unit 112.

[0057] In the crisper bin container 76, the lid 92 can be provided with the small, resilient latch member 150 that releasably keeps the lid 92 secured onto the container body 90 so that the hermetic seal as previously described is effected. In the container 10, the lid is provided with a plurality of pivotal latch members 152 that can snap onto a rim 154 formed about the upper ends of the upstanding walls 22 for effecting the hermetic seal as described.

[0058] While there have been illustrated and described particular embodiments of the present invention, it will be appreciated that numerous changes and modifications will occur to those skilled int eh art, and it is intended in the appended claims to cover all those changes and modifications which fall within the true spirit and scope of the present invention. 

We claim:
 1. A container for carrying atmospherically sensitive items with a minimum of damage and over long durations, the container comprising: a plurality of generally rigid walls bounding an internal space with the rigid walls protecting the items received in the space against damage; a window opening formed at a predetermined position in one of the rigid walls; and a membrane mounted to the one of the rigid walls at the window opening thereof, the membrane being configured to exchange gases between the internal space and the external ambient environment to substantially maintain atmospheric conditions in the container internal space optimized for long duration containment of the atmospherically sensitive items therein.
 2. The container of claim 1 wherein the membrane is a flexible thin film member, and a grate assembly secured to the one wall about the opening to protect the thin film membrane from damage.
 3. The container of claim 1 including a detachable connection between the membrane and the one wall to allow membranes to be interchanged.
 4. The container of claim 1 including at least one grate member and removable fasteners for releasable securing the grate member to the one container wall over the membrane.
 5. The container of claim 4 wherein the at least one grate member comprises a pair of grate members attached together to sandwich the membrane therebetween.
 6. The container of claim 1 wherein the membrane is incorporated in a modular unit that is releaseably secured in the window opening.
 7. The container of claim 6 wherein the modular unit and the one wall of the container include one of a bayonet connection and cooperating threads therebetween to allow the unit to be turned onto and off from the container.
 8. The container of claim 1 wherein the membrane comprises a plurality of membranes with each membrane configured for optimizing atmospheric conditions for a specific type of item and including indicia to allow the appropriate membrane to be selected for use with the container based on the item to be carried therein.
 9. The container of claim 8 wherein the indicia comprises color codes for different items that are to be carried in the container.
 10. The container of claim 1 wherein the rigid walls include a bottom wall and side walls upstanding therefrom, the side walls having an upper end which defines an opening to the internal space, and a lid sized to close the opening, and a lip flange projecting laterally outward from the upper end of the side walls to allow the container to slide along support rail structure in refrigerators for use as a crisper bin therein.
 11. The container of claim 10 wherein the upper end of the side walls and the lid include cooperating seal portions and latch portions so that with the latch portions engaged for clamping the lid onto the upper end of the side walls, the seal portions are tightly compressed together for hermetically sealing the container interior space so that gas exchange occurs only through the membrane.
 12. A container for keeping perishable items fresh and free from damage, the container comprising: a container body having strong rigid walls for withstanding impacts to minimize damage to the items therein; a lid for closing an interior space of the container when seated on the container body; a hermetic seal between the lid and the container body to seal the container interior from the external environment; a port opening in the container body; a plurality of semi-permeable membranes for regulating exchange of gases in a predetermined manner between the container interior space and external environment, the membranes being coded based on the manner in which they regulate gas exchange therethrough which provides optimized atmospheric conditions in the container interior space for a particular perishable item; and a removable mount for releasably attaching a selected one of the membranes to the container body at the port opening thereof to allow the atmospheric conditions in the interior space to be substantially tailored to the item to be carried therein.
 13. The container of claim 12 wherein the removable mount comprises a grate assembly secured to the container body about the opening thereof.
 14. The container of claim 13 wherein the grate assembly includes an outer grate member that can be removed to expose the membrane thereunder for changing membranes on the container body.
 15. The container of claim 12 wherein the removable mount comprises a modular unit carrying a predetermined one of the membranes therein.
 16. The container of claim 15 wherein the modular unit and the container body at the opening thereof have either a threaded or a bayonet connection therebetween.
 17. The container of claim 16 wherein the modular unit has a shank sized to fit in the opening and an enlarged head sized to engage against the container body about the opening thereof and in which the membrane is carried.
 18. A semi-permeable membrane unit for being removably secured to a container that carries perishable items in an internal space thereof, the unit comprising: a membrane having predetermined gas exchange characteristics to provide a controlled atmosphere in the container space optimized for long duration containment of a specific type of a perishable item to be carried therein; a generally rigid grate portion having a plurality of small openings formed therein; a removable mount for releasably securing the membrane at an opening in a wall of the container and including the grate portion such that air flow between the ambient exterior and container interior space occurs through the membrane and grate openings.
 19. The membrane unit of claim 18 wherein the grate portion and removable mount are integrated in a module that carries the membrane therein.
 20. The membrane unit of claim 18 wherein the grate portion comprises a distinct grate member, and the removable mount includes the grate member and fasteners that releasably secure the grate member to the container wall about the opening thereof.
 21. A crisper bin container for keeping perishable items fresh in a refrigerator, the crisper bin container comprising: a container body having an internal space in which the items are carried; a bottom wall of the container body and front, back and side walls of the container body upstanding from the bottom wall forming an opening at upper ends thereof; a lid sized to close the opening and including a hinge for allowing at least a portion of the lid to be pivoted open for accessing items in the internal space through the opening while staying connected to the container body; a hermetic seal between the lid and the lip flange with the lid pivoted closed; a window opening in one of the upstanding walls of the container body; and a semi-permeable membrane attached to the one wall at the window opening to regulate gas exchange between the container interior space and the exterior environment through the window opening for substantially avoiding accelerated deterioration of perishable items in the container space.
 22. The crisper bin container of claim 21 wherein the membrane is carried in a removable mount, the window opening is in the front wall, and a releasable connection between the front wall and the removable mount to provide forward access to the unit for changing units and membranes carried therewith.
 23. The crisper bin container of claim 22 wherein the releasable connection is either a tooless connection or formed by removable fasteners.
 24. The crisper bin container of claim 21 including a lip flange extending laterally out from the upper ends of the side walls for slidingly engaging on rail structure in the refrigerator.
 25. The crisper bin container of claim 21 wherein the lid includes a projecting handle portion for pulling or pushing the bin container for sliding along the refrigerator rail structure. 